Flash
When Omen of Storms enters, discard a card, then draw two cards.
{2}{R}, Sacrifice Omen of Storms: Scry 2.

Flash
When Omen of Victory enters, create a 0/0 white Army creature token, then put two +1/+1 counters on it.
{2}{W}, Sacrifice Omen of Victory: Scry 2.

Flying, first strike, lifelink
Landfall — Whenever a land you control enters, other creatures you control get +2/+2 until end of turn.

First strike
Landfall — Whenever a land you control enters, other creatures you control get +1/+1 until end of turn.
{2}{R}{W}{B}: Transform Omenhorn.

Ominous Quag enters tapped.
{T}: Add {W} or {B}.
{2}{W}{B}, {T}, Sacrifice Ominous Quag: Draw a card.

Your maximum hand size is zero.
Pay 1 life: Draw a card. Activate only as a sorcery.

Whenever Omnoid Destroyer or another artifact you control enters, artifact creatures you control gain deathtouch until end of turn.

Whenever Opal-Eye Allseer enters or you cast a noncreature spell, create a 1/1 white Bird creature token with flying.
Wander—{1}{U}, Exile two instant and/or sorcery cards from your graveyard.

When Opal-Eye Caretaker enters, put a +1/+1 counter on each creature you control that entered this turn and wasn't cast from your hand.
Wander {1}{W}

Flying, haste
As an additional cost to cast spells with flashback, you may pay {1}{R}. When you do, return Opal-Eye Phoenix from your graveyard to the battlefield.

Whenever you spend at least five mana to cast a spell, untap Opal-Eye Runeweaver.
{T}: Untap another target permanent not named Opal-Eye Runeweaver. Activate only as a sorcery.

Open Air Boardwalk enters tapped.
{T}: Add {G} or {W}.
{4}: Make a pledge. Activate only as a sorcery.

When Opulent Roughrider enters or leaves the battlefield, surveil 1, then you may reveal the top card of your library. If that card has the same name as a permanent you control or a card in your graveyard, put it into your hand.
Wander {4}{U}{U}

Vigilance
Whenever you attack, bless target creature.

Whenever you cast an instant or sorcery spell, Orbinoid gets +1/+1 and gains trample until end of turn.

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Athreos.
When you sacrifice Ordeal of Athreos, return target creature card from your graveyard to the battlefield.

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Ephara.
When you sacrifice Ordeal of Ephara, return up to two target nonland permanents to their owner's hand.

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Karametra.
Whenever you sacrifice Ordeal of Karametra, put a +1/+1 counter on each creature you control. Untap them.

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Karda.
Whenever you sacrifice Ordeal of Karda, creatures you control get +2/+0 until end of turn.

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Pharika.
Whenever you sacrifice Ordeal of Pharika, creatures your opponents control get -2/-2 until end of turn.

Creatures you control have menace as long as they are attacking players with eight or more cards in their graveyard.
Whenever you attack, each defending player mills two cards. If a land card was milled this way, put a +1/+1 counter on Orestes.

Outlands Prowler has first strike as long as it's your turn.
Landfall — Whenever a land you control enters, Outlands Prowler gets +2/+2 until end of turn.

When Overbearing Researcher enters, put a +1/+1 counter on target creature.
Each creature you control has ward {X}, where X is the number of counters on that creature.

Trample
Solidarity
{G}, Sacrifice an enchantment: Ozanwood Huntsman gets +2/+2 until end of turn.

At the beginning of your first main phase, you may add one mana of any type.